Enable parallel execution of tests

[carbolymer]

Changelog

- description: |
    Enable parallel execution of tests
# uncomment types applicable to the change:
  type:
  # - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - improvement    # QoL changes e.g. refactoring
  # - bugfix         # fixes a defect
   - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...

Context

See an explanation in similar PR in node: IntersectMBO/cardano-node#5692

Before change:

All 204 tests passed (16.75s)
Test suite cardano-cli-golden: PASS
...
All 22 tests passed (3.94s)
Test suite cardano-cli-test: PASS

After change

All 204 tests passed (12.38s)
Test suite cardano-cli-golden: PASS
...
All 22 tests passed (1.97s)
Test suite cardano-cli-test: PASS

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[smelc]

New semaphore mechanism LGTM 🍾

[newhoggy]

If this test is run once, how does concurrent execution cause it to run multiple times?

[carbolymer]

It's executed once. The problem is that this golden file is shared between multiple test cases, which are executed concurrently. So when we're testing golden files regeneration, two test cases see the file missing so they try to recreate file at the same time. This somehow is an issue on windows, which results in an exception here.